Seawater is evaporated at the front of the greenhouse to create cool humid conditions inside. A proportion of the evaporated seawater is then condensed as fresh water that can be used to irrigate the crops. Excess freshwater created in the Seawater Greenhouse can be used to irrigate additional crops grown outside the greenhouse.

The air going into the greenhouse is first cooled and humidified by seawater, which trickles over the first evaporator. This provides good climate conditions for the crops. As the air leaves the growing area, it passes through the second evaporator over which seawater is flowing. This seawater has been heated by the sun in a network of pipes above the growing area, making the air much hotter and more humid. It then meets a series of vertical pipes through which cool seawater passes. When the hot humid air meets the cool surfaces, fresh water will condense as droplets that run down to the base where they can be collected.

The cool and humid conditions in the greenhouse enable crops to grow with very little water. When crops are not stressed by excessive transpiration, both the yield and the quality are higher.

The simplicity of the process imitates the hydrological cycle where seawater heated by the sun evaporates, cools down to form clouds, and returns to the earth as rain, fog or dew.